a. Field of the Invention
The present invention pertains generally to electrophysiological devices and methods for diagnosing and treating biological tissue and, more particularly, to diagnostic and therapeutic catheters having a laminate-coated braid assembly.
b. Background Art
Catheters are used for an ever-growing number of procedures. For example, catheters are used for diagnostic, therapeutic, and ablative procedures, to name just a few examples. Typically, the catheter is manipulated through a patient's vasculature and to the intended site, for example, a site within the patient's heart. The catheter typically carries one or more electrodes, which may be used for ablation, diagnosis, or the like.
Since the path through the patient's vasculature to the intended site is often long and tortuous, steering forces typically must be transmitted over relatively great distances. Accordingly, it is desirable for a catheter to have sufficient flexibility to substantially conform to the patient's vasculature and yet resist kinking as it does so Kinking is often the result of a localized failure of the material of the catheter when localized stresses exceed the yield strength of the material. To provide flexibility and kink resistance, many extant catheters include metallic wire braiding.
Many catheters also include one or more electrical wires for energizing electrodes or other energy delivery or diagnostic elements. The electrical wires must be insulated from the wire braiding, if present, and other internal components in order to prevent electrical shorts. In some cases, the braid wires may serve as the electrical wires. In order for braid wires to be implemented as the electrical wires, the braid wires must be insulated, otherwise contact between adjacent braid wires may induce electrical shorts. Most existing insulative coatings are too stiff for use in steerable devices and tend to result in tears that cause electrical shorts after only a few articulations of the device, for example as few as 10-12 articulations. What is needed, therefore, are flexible braid assemblies having insulated braid members that can withstand a greater number of articulations without tearing.